Have a new 2012 Genny, 3.8L V6... has about 1200 miles on it now and is, for me, broken in fine. On highway trips to Tucson and back, this past weekend, we have been averaging 32 mph (65mph (adaptive cruse set to 67 mph) 4-lane to I-10, then cruise set at 78 mph to Tucson w/ adaptive cruise...